Breast Cancer

Breast cancer is where malignant cancer cells are found in the breast tissues. Breast cancer usually develops from the ducts in the breast. The cancerous cells may then spread throughout the breast and to other parts of the body.

How Common is Breast Cancer?

Breast cancer is the leading cause of cancer death in women today in Singapore. Almost 1 in 16 women in Singapore will be diagnosed with breast cancer in her lifetime. Chinese women have a higher chance of developing breast cancer compared to Malay and Indian women. The highest incidence of breast cancer is in women between 40 and 69 years old. The good news is that with earlier detection and improved treatment, more women are surviving the disease.

What Causes Breast Cancer?

The exact causes of this cancer are unknown, but there are many known risk factors such as a family history of breast cancer. Any woman can be at risk, especially for those who are 40 and above. Effective treatment is available for breast cancer if it is detected early. Therefore, regular screening is very important to help detect breast cancer in its early stages.

How is Breast Cancer Diagnosed?

Clinical Examination – Especially if there is a lump or nipple discharge, or an unusual breast change is detected.

Mammogram – This is special x-ray imaging that can detect abnormal masses in the breast such as calcium deposits, cysts and tumours.

Ultrasound Scan – Used to examine abnormalities found the mammogram. An ultrasound scan can distinguish between a solid mass, which may be a cancer, or a fluid-filled cyst which is usually not cancer.

Magnetic Resonance Imaging (MRI) – A MRI scan can better assess areas of concern in the breast. This is particularly useful for younger women because this group tends to have higher breast tissue density, reducing the effectiveness of conventional imaging tests such as the mammogram and ultrasound in detecting breast cancer.

What is a biopsy?

To confirm breast cancer, a biopsy will have to be performed in which cells are removed and examined under a microscope.

Common biopsy techniques:

Fine Needle Aspiration (FNA)

Core Needle or Tru-cut Biopsy

Excision Biopsy

How is Breast Cancer Assessed?

Stages / Extent of Spread

Stage

Extent of Spread

Average 5-year Survival Rate (%)*

0

Non-invasive cancer

99

I

Small invasive cancer

(less than 2cm without spreading to the axillary lymph nodes)

90

II

Invasive cancer

(between 2 – 5cm or/with lymph nodes invasion)

70

III

Large invasive cancer

(more than 5cm with skin invasion or spread to multiple lymph nodes)

40

IV

Widespread or metastatic cancer

20

*Individual patients may have a different experience depending on the specific characteristics of their breast cancer, and which therapies can be used to target their cancer.

These characteristics of breast cancer can impact the chances of relapse and affect the patient’s survival rate.

Tumour Grade Histologic Grade

This refers to how much the tumour cells resemble normal cells when viewed under the microscope, rated from 1 to 3. Grade 3 tumours contain very abnormal and rapidly growing cancer cells. The higher the histologic grade, the greater the chance of breast cancer relapsing.

Lymph Nodes

The number of lymph nodes that is in the armpit, on the same side of the affected breast, is an important indicator. A higher number of positive nodes will often result in a worse outcome and warrants more aggressive treatments.

Tumour Size

In general, the larger the size of the tumour, the greater the chance of breast cancer recurrence.

Oestrogen/Progesterone Receptors

Close to 2/3 of all breast cancers contain significant levels of oestrogen and/or progesterone receptors. They are referred to as oestrogen receptor positive (ER+) tumours. ER+ tumours tend to grow less aggressively and may respond favourably to treatment with hormones.

HER2

HER2 is a protein found on the surface of certain cancer cells. A tumour is described as HER2-positive if tests show an excess of the HER2 protein on its cells. Tumours that are HER2-positive tend to grow more quickly than other types of breast cancer. 20-25% of all breast cancers have HER2-positive tumours.

Knowing if a cancer is HER2-positive can affect the choice of treatment because women with such tumours can benefit from HER2-targeted therapies. These include drugs such as trastuzumab (Herceptin®), pertuzumab (Perjeta®) or TDM-1 (Kadcyla®).

How is Breast Cancer Treated?

The treatment of breast cancer and the chances of recovery depend on whether the cancer is only in the breast or has spread to other places in the body. More factors that can determine the treatment options and prognosis include the type of cancer, specific characteristics of the cancer cells, whether the cancer is found in the other breast, the patient’s age, menopausal status (whether the patient still has menstrual periods) and the patient’s general health.

Surgery

Surgery can be a direct way to remove cancer from the body. Forms of surgery include:

1) Breast-conserving surgery

Lumpectomy or wide local excision – Removal of the cancer and a small amount of surrounding tissue

Quadrantectomy – Removal of the quarter of the breast where the cancer is found

2) Mastectomy – Removal of the whole breast

During the breast surgery, some of the lymph nodes under the armpit may also be removed for examination.

Radiotherapy

Radiotherapy uses high-energy rays to target and kill cancer cells. It is used to kill cancer cells remaining in or around the breast, lowering the chances of the cancer returning in the breast.

Radiotherapy can be vital after a breast-conserving surgery like lumpectomy, since much of the breast tissue is left intact.

Most women who have a mastectomy do not need radiotherapy. However it can be used to treat the chest wall and the lymph nodes in the armpit if the risk of recurrence is high.